The MRI apparatus is an imaging diagnostic apparatus which magnetically excites nuclear spins of an object set in a static magnetic field with RF (radio frequency) signals having the Larmor frequency and reconstructs an image based on MR (magnetic resonance) signals generated due to the excitation.
In MRI apparatuses, a technology called direct sampling, which performs AD (analog to digital) conversion directly without a frequency conversion to a lower frequency (down conversion) of analog MR echo signals, has been developed. When direct sampling of MR signals is performed, down conversion is performed to digitalized MR echo signals after the AD conversion.
An imaging system including a static field magnet, gradient coils, and RF coils and the like out of elements of an MRI apparatus is placed in an imaging room. On the other hand, a transmission system of RF signals and a reception system of MR signals are placed in a machine room magnetically shielded from the imaging room in order to avoid influence of magnetic fields.
However, there are needs to introduce an MRI apparatus to a medical institution, which has difficulty in securing a sufficient space for installing an MRI apparatus, in recent years. Moreover, there are needs to change an outdated MRI apparatus of a low magnetic field type into an updated MRI apparatus of a high magnetic field type as well. In this case, widths of an imaging room and a machine room which were designed for installing an outdated MRI apparatus of a low magnetic field type may possibly be insufficient. From such background, it is desired to be able to install a reception system of MR signals in an imaging room.
Accordingly, it is an object of the present invention to provide a magnetic resonance imaging apparatus and a magnetic resonance imaging method which can place at least a part of a reception system, for receiving MR signals by direct sampling, in an imaging room.